1. Field of the Invention
The present invention relates to information processing devices made up of various types of electronic devices and the accessory control devices that are installed in them and the accessory control devices and the information processing methods used in these information processing devices, and more specifically it relates to configurations that notify of the completion of transfer in cases in which data is transferred from the electronic device to the accessory control device and the information processing methods used in those cases.
2. Related Art
In recent years, personal computers, word processors, workstations and other electronic devices founded on digital operation, and printers, facsimile machines, electronic pocketbooks, electronic musical instruments, electronic cooking appliances, electronic cameras and other electronic devices containing microprocessors are being used in all areas of society. Further, the use of microprocessors is spreading to automobiles, robots and machine tools, as well as all types of electric products.
Devices founded on this type of digital logic operation have the potential of flexible control and data processing as compared with simple feedback control, etc., realized with hardware only, and they also have the advantage of being able to change essential functions by changing the software. Therefore, it is possible to realize completely different control within the same hardware just by changing the contents of the ROM where procedures (i.e., software programs) are stored, or loading a new program to the main memory from an external device such as a floppy disk. Another advantage is the ability to upgrade functions just by changing the software.
However, since the throughput of the processor that actually performs control is dependent on the hardware, i.e., number of operations per unit time, number of bits that can be handled at one time and width of the bus that performs data transfer, improvement by upgrading the software is limited to only improved useability, and any significant improvement in the performance of the existing electronic device cannot be achieved. Further, upgrading by changing the software requires replacement of the ROM if the software is burned into the ROM, thus making it difficult in many cases. Therefore, upgrading the software is difficult in cases except in which ROM replacement is designed into the device from the beginning or the software is supplied on a replaceable medium such as a floppy disk.
In personal computers, for example, accelerators are used which improve the functionality of the entire computer by completely replacing the microprocessor, but this requires replacement of the CPU on the motherboard or other difficult operations that cannot by performed by just anyone. In electronic devices intended for use as a personal computer, a connector is often provided for the installation of ROM cards, font cartridges, etc. If an accessory control device could be installed in this connector, the functionality of the electronic device could be improved, added to or changed, but examination of the data transfer bus of these connectors will show that many of them are read-only signal lines as seen from the internal processor, in which case an accelerator cannot be installed in the connector since it cannot receive data from the processor in the electronic device.
Normally, no consideration has been made regarding the improvement or changing of the functionality of printers, facsimile machines, electronic pocketbooks, electronic musical instruments, electronic cooking appliances, electronic cameras and other consumer electronics containing a microprocessor, electrical equipment for automobiles, robots, machine tools and other industrial electronic apparatus, and all types of electric appliances, and even if a connector for expansion is provided, it is generally restricted to the function of only reading out data. This problem is described in detail below using a page printer as an example.
In recent years, the diffusion of laser printers and other page printers has become extremely widespread, and high speed output devices for data from computers have become common. In the case of laser printers, their resolutions range from 240 to 800 dots per inch (DPI), and printers capable of printing several pages a minute are being developed. These printers employ a xerography unit that uses a photosensitive drum as the engine for printing, and since they continuously perform each of the charging, exposure, toner application and transfer processes in sync with the rotation of the photosensitive drum, printing processing begins after the image for a single page is stored in memory.
Therefore, the memory provided in page printers for image development must have the capacity to hold the image for at least one page, and if compression of image data is not performed, the capacity is determined by the resolution and the size of the paper that can be processed. For example, in the case of a resolution of 300 DPI and a paper size of 8 inches by 10 inches, then 7,200,000 (8.times.10.times.300.times.300) dots must be manipulated and at least a 0.9-megabyte memory is required.
In printers with a function that receives character codes, row and column pitch and other information as print data and expands this into the image, or in printers that receive a program described by a page description language and expand the image by interpreting it, it is necessary to calculate and produce a bit image based on this print data, which greatly reduces the overall processing speed compared to simple bit image transfer. That is, the processing speed of a printer is determined mainly by the throughput of the processor that performs processing and memory access time and falls far short of the printing throughput of the xerography unit itself.
For example, in a page printer capable of printing 10 pages in one minute, only six seconds is allowed to prepare the image data for one page of printing, and to develop all of this 0.9 megabytes of data in this period of time means that the processing time allowed for one byte is a mere 6.67 microseconds (6 s/0.9 MB). This processing speed can possibly be realized with one of the high-speed RISC type processors currently available on the market. In contrast to this, there are currently many xerography units capable of printing 10 pages per minute. Therefore, the throughput of the controllers that process print data has become a bottleneck in improving overall print speeds.
For this reason, there are cases in which the image developing throughput is always below the xerography unit's throughput in prior art laser printers, and even if it becomes possible to obtain a processor with a high image developing throughput as microprocessor technology advances, it is impossible to improve functionality later. There are some page printers whose functionality can be improved by providing an expansion slot and installing a cartridge with built-in fonts or programs in it, but the structure of the data bus of the slot connector is read only from the cartridge connector and data cannot be transferred to the cartridge and processed.
The purpose of the accessory control device, information processing device and information processing method of the invention is to solve this problem and make it possible to improve, change or add to the overall functionality of electronic devices.